#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
故障转移机制模块
实现故障检测、自动恢复和故障转移功能
"""

import time
import logging
import threading
from typing import Dict, List, Optional, Any, Callable
from dataclasses import dataclass
from enum import Enum
import json

logger = logging.getLogger(__name__)


class HealthStatus(Enum):
    """健康状态枚举"""
    HEALTHY = "healthy"
    UNHEALTHY = "unhealthy"
    DEGRADED = "degraded"
    UNKNOWN = "unknown"


class FaultType(Enum):
    """故障类型枚举"""
    NETWORK = "network"
    INSTANCE = "instance"
    SERVICE = "service"
    API = "api"
    STORAGE = "storage"
    UNKNOWN = "unknown"


@dataclass
class HealthCheck:
    """健康检查数据类"""
    service_id: str
    service_type: str
    status: HealthStatus
    last_check_time: float
    response_time: float
    error_message: str = ""
    retry_count: int = 0
    max_retries: int = 3


@dataclass
class FaultEvent:
    """故障事件数据类"""
    fault_id: str
    fault_type: FaultType
    service_id: str
    severity: str
    description: str
    timestamp: float
    resolved: bool = False
    resolution_time: Optional[float] = None


class HealthChecker:
    """健康检查器"""
    
    def __init__(self, structured_logger):
        """
        初始化健康检查器
        
        Args:
            structured_logger: 结构化日志记录器
        """
        self.structured_logger = structured_logger
        
        # 健康检查配置
        self.check_interval = 30  # 30秒检查一次
        self.timeout = 10  # 10秒超时
        self.max_retries = 3
        
        # 健康检查结果
        self.health_checks: Dict[str, HealthCheck] = {}
        self.health_lock = threading.Lock()
        
        # 故障事件
        self.fault_events: List[FaultEvent] = []
        self.fault_lock = threading.Lock()
        
        # 运行状态
        self.running = False
        self.checker_thread = None
        
        # 健康检查函数
        self.check_functions: Dict[str, Callable] = {}
        
        logger.info("健康检查器已初始化")
    
    def start(self) -> None:
        """启动健康检查"""
        if self.running:
            return
        
        self.running = True
        self.checker_thread = threading.Thread(target=self._check_loop, daemon=True)
        self.checker_thread.start()
        logger.info("健康检查已启动")
    
    def stop(self) -> None:
        """停止健康检查"""
        self.running = False
        if self.checker_thread:
            self.checker_thread.join(timeout=5)
        logger.info("健康检查已停止")
    
    def register_service(self, service_id: str, service_type: str, check_function: Callable) -> None:
        """
        注册服务健康检查
        
        Args:
            service_id: 服务ID
            service_type: 服务类型
            check_function: 健康检查函数
        """
        self.check_functions[service_id] = check_function
        
        # 初始化健康检查记录
        with self.health_lock:
            self.health_checks[service_id] = HealthCheck(
                service_id=service_id,
                service_type=service_type,
                status=HealthStatus.UNKNOWN,
                last_check_time=0,
                response_time=0,
                max_retries=self.max_retries
            )
        
        logger.info(f"注册服务健康检查: {service_id} ({service_type})")
    
    def _check_loop(self) -> None:
        """健康检查循环"""
        while self.running:
            try:
                self._perform_health_checks()
                time.sleep(self.check_interval)
            except Exception as e:
                logger.error(f"健康检查循环错误: {e}")
                time.sleep(60)
    
    def _perform_health_checks(self) -> None:
        """执行健康检查"""
        for service_id, check_function in self.check_functions.items():
            try:
                self._check_service_health(service_id, check_function)
            except Exception as e:
                logger.error(f"检查服务健康状态失败: {service_id}, 错误: {e}")
    
    def _check_service_health(self, service_id: str, check_function: Callable) -> None:
        """检查单个服务健康状态"""
        start_time = time.time()
        
        try:
            # 执行健康检查
            result = check_function()
            
            response_time = time.time() - start_time
            
            # 更新健康检查记录
            with self.health_lock:
                if service_id in self.health_checks:
                    health_check = self.health_checks[service_id]
                    health_check.last_check_time = time.time()
                    health_check.response_time = response_time
                    
                    if result:
                        health_check.status = HealthStatus.HEALTHY
                        health_check.error_message = ""
                        health_check.retry_count = 0
                    else:
                        health_check.status = HealthStatus.UNHEALTHY
                        health_check.error_message = "健康检查失败"
                        health_check.retry_count += 1
                        
                        # 检查是否需要记录故障事件
                        if health_check.retry_count >= health_check.max_retries:
                            self._record_fault_event(service_id, "健康检查连续失败")
            
        except Exception as e:
            response_time = time.time() - start_time
            error_message = str(e)
            
            # 更新健康检查记录
            with self.health_lock:
                if service_id in self.health_checks:
                    health_check = self.health_checks[service_id]
                    health_check.last_check_time = time.time()
                    health_check.response_time = response_time
                    health_check.status = HealthStatus.UNHEALTHY
                    health_check.error_message = error_message
                    health_check.retry_count += 1
                    
                    # 检查是否需要记录故障事件
                    if health_check.retry_count >= health_check.max_retries:
                        self._record_fault_event(service_id, f"健康检查异常: {error_message}")
    
    def _record_fault_event(self, service_id: str, description: str) -> None:
        """记录故障事件"""
        try:
            fault_event = FaultEvent(
                fault_id=f"fault_{service_id}_{int(time.time())}",
                fault_type=FaultType.SERVICE,
                service_id=service_id,
                severity="high",
                description=description,
                timestamp=time.time()
            )
            
            with self.fault_lock:
                self.fault_events.append(fault_event)
                
                # 保持最近100个故障事件
                if len(self.fault_events) > 100:
                    self.fault_events = self.fault_events[-100:]
            
            # 记录故障日志
            self.structured_logger.log_alert(
                alert_type="fault_detected",
                severity="high",
                message=f"检测到故障: {service_id}",
                details={
                    "service_id": service_id,
                    "description": description,
                    "fault_id": fault_event.fault_id
                }
            )
            
            logger.warning(f"记录故障事件: {service_id} - {description}")
            
        except Exception as e:
            logger.error(f"记录故障事件失败: {e}")
    
    def get_health_status(self) -> Dict[str, Any]:
        """获取健康状态"""
        with self.health_lock:
            healthy_count = sum(1 for hc in self.health_checks.values() if hc.status == HealthStatus.HEALTHY)
            unhealthy_count = sum(1 for hc in self.health_checks.values() if hc.status == HealthStatus.UNHEALTHY)
            total_count = len(self.health_checks)
            
            return {
                "total_services": total_count,
                "healthy_services": healthy_count,
                "unhealthy_services": unhealthy_count,
                "health_rate": healthy_count / total_count if total_count > 0 else 0,
                "services": {
                    service_id: {
                        "status": hc.status.value,
                        "last_check_time": hc.last_check_time,
                        "response_time": hc.response_time,
                        "error_message": hc.error_message,
                        "retry_count": hc.retry_count
                    }
                    for service_id, hc in self.health_checks.items()
                }
            }
    
    def get_fault_events(self, limit: int = 10) -> List[Dict[str, Any]]:
        """获取故障事件"""
        with self.fault_lock:
            recent_events = self.fault_events[-limit:] if self.fault_events else []
            
            return [
                {
                    "fault_id": event.fault_id,
                    "fault_type": event.fault_type.value,
                    "service_id": event.service_id,
                    "severity": event.severity,
                    "description": event.description,
                    "timestamp": event.timestamp,
                    "resolved": event.resolved,
                    "resolution_time": event.resolution_time
                }
                for event in recent_events
            ]
    
    def resolve_fault(self, fault_id: str) -> bool:
        """解决故障"""
        try:
            with self.fault_lock:
                for event in self.fault_events:
                    if event.fault_id == fault_id and not event.resolved:
                        event.resolved = True
                        event.resolution_time = time.time()
                        
                        # 记录解决日志
                        self.structured_logger.log_alert(
                            alert_type="fault_resolved",
                            severity="info",
                            message=f"故障已解决: {fault_id}",
                            details={
                                "fault_id": fault_id,
                                "service_id": event.service_id,
                                "resolution_time": event.resolution_time
                            }
                        )
                        
                        logger.info(f"故障已解决: {fault_id}")
                        return True
            
            return False
            
        except Exception as e:
            logger.error(f"解决故障失败: {e}")
            return False


class FaultToleranceManager:
    """故障转移管理器"""
    
    def __init__(self, health_checker: HealthChecker, load_balancer, hai_client, structured_logger):
        """
        初始化故障转移管理器
        
        Args:
            health_checker: 健康检查器
            load_balancer: 负载均衡器
            hai_client: HAI客户端
            structured_logger: 结构化日志记录器
        """
        self.health_checker = health_checker
        self.load_balancer = load_balancer
        self.hai_client = hai_client
        self.structured_logger = structured_logger
        
        # 故障转移配置
        self.auto_failover_enabled = True
        self.failover_timeout = 60  # 60秒故障转移超时
        self.recovery_check_interval = 300  # 5分钟恢复检查间隔
        
        # 故障转移状态
        self.failed_services: Dict[str, float] = {}  # 服务ID -> 失败时间
        self.recovery_attempts: Dict[str, int] = {}  # 服务ID -> 恢复尝试次数
        
        # 运行状态
        self.running = False
        self.manager_thread = None
        
        logger.info("故障转移管理器已初始化")
    
    def start(self) -> None:
        """启动故障转移管理"""
        if self.running:
            return
        
        self.running = True
        self.manager_thread = threading.Thread(target=self._management_loop, daemon=True)
        self.manager_thread.start()
        logger.info("故障转移管理已启动")
    
    def stop(self) -> None:
        """停止故障转移管理"""
        self.running = False
        if self.manager_thread:
            self.manager_thread.join(timeout=5)
        logger.info("故障转移管理已停止")
    
    def _management_loop(self) -> None:
        """管理循环"""
        while self.running:
            try:
                self._check_failed_services()
                self._attempt_recovery()
                time.sleep(self.recovery_check_interval)
            except Exception as e:
                logger.error(f"故障转移管理循环错误: {e}")
                time.sleep(60)
    
    def _check_failed_services(self) -> None:
        """检查失败的服务"""
        try:
            health_status = self.health_checker.get_health_status()
            
            for service_id, service_info in health_status["services"].items():
                if service_info["status"] == "unhealthy":
                    if service_id not in self.failed_services:
                        # 新发现的失败服务
                        self.failed_services[service_id] = time.time()
                        self.recovery_attempts[service_id] = 0
                        
                        # 执行故障转移
                        if self.auto_failover_enabled:
                            self._execute_failover(service_id)
                else:
                    # 服务已恢复
                    if service_id in self.failed_services:
                        del self.failed_services[service_id]
                        if service_id in self.recovery_attempts:
                            del self.recovery_attempts[service_id]
                        
                        logger.info(f"服务已恢复: {service_id}")
            
        except Exception as e:
            logger.error(f"检查失败服务错误: {e}")
    
    def _execute_failover(self, service_id: str) -> None:
        """执行故障转移"""
        try:
            logger.info(f"执行故障转移: {service_id}")
            
            # 记录故障转移事件
            self.structured_logger.log_alert(
                alert_type="failover_executed",
                severity="high",
                message=f"执行故障转移: {service_id}",
                details={
                    "service_id": service_id,
                    "failover_time": time.time()
                }
            )
            
            # 根据服务类型执行不同的故障转移策略
            if "server" in service_id or "instance" in service_id:
                self._failover_server(service_id)
            elif "api" in service_id:
                self._failover_api(service_id)
            else:
                self._failover_generic(service_id)
            
        except Exception as e:
            logger.error(f"执行故障转移失败: {service_id}, 错误: {e}")
    
    def _failover_server(self, service_id: str) -> None:
        """服务器故障转移"""
        try:
            # 从负载均衡器移除失败的服务器
            self.load_balancer.remove_server(service_id)
            
            # 创建新的服务器实例
            new_instance_id = self.hai_client.create_instance()
            
            if new_instance_id:
                # 添加到负载均衡器
                from .task_distribution import Server
                server = Server(
                    server_id=new_instance_id,
                    region="ap-beijing",  # 默认地域
                    gpu_type="basic",     # 默认GPU类型
                    status="HEALTHY",
                    created_time=time.time(),
                    endpoint=f"http://{new_instance_id}.hai.tencentcloud.com"
                )
                self.load_balancer.add_server(server)
                
                logger.info(f"服务器故障转移成功: {service_id} -> {new_instance_id}")
            else:
                logger.error(f"服务器故障转移失败: 无法创建新实例")
                
        except Exception as e:
            logger.error(f"服务器故障转移失败: {e}")
    
    def _failover_api(self, service_id: str) -> None:
        """API故障转移"""
        try:
            # API故障转移通常涉及切换到备用API端点
            logger.info(f"API故障转移: {service_id}")
            
            # 这里可以实现具体的API故障转移逻辑
            # 例如：切换到备用API服务器、启用缓存等
            
        except Exception as e:
            logger.error(f"API故障转移失败: {e}")
    
    def _failover_generic(self, service_id: str) -> None:
        """通用故障转移"""
        try:
            logger.info(f"通用故障转移: {service_id}")
            
            # 通用故障转移策略
            # 例如：重启服务、清理资源、发送通知等
            
        except Exception as e:
            logger.error(f"通用故障转移失败: {e}")
    
    def _attempt_recovery(self) -> None:
        """尝试恢复失败的服务"""
        try:
            current_time = time.time()
            
            for service_id, fail_time in list(self.failed_services.items()):
                # 检查是否超过恢复检查间隔
                if current_time - fail_time > self.recovery_check_interval:
                    # 尝试恢复服务
                    if self._try_recover_service(service_id):
                        # 恢复成功
                        del self.failed_services[service_id]
                        if service_id in self.recovery_attempts:
                            del self.recovery_attempts[service_id]
                        
                        logger.info(f"服务恢复成功: {service_id}")
                    else:
                        # 恢复失败，增加尝试次数
                        self.recovery_attempts[service_id] = self.recovery_attempts.get(service_id, 0) + 1
                        
                        if self.recovery_attempts[service_id] >= 5:  # 最多尝试5次
                            logger.error(f"服务恢复失败，已达到最大尝试次数: {service_id}")
                            # 可以考虑永久移除该服务或发送人工干预通知
            
        except Exception as e:
            logger.error(f"尝试恢复服务错误: {e}")
    
    def _try_recover_service(self, service_id: str) -> bool:
        """尝试恢复单个服务"""
        try:
            # 这里可以实现具体的服务恢复逻辑
            # 例如：重启服务、重新部署、清理状态等
            
            logger.info(f"尝试恢复服务: {service_id}")
            
            # 执行真实的恢复操作
            return self._perform_service_recovery(service_id)
            
        except Exception as e:
            logger.error(f"恢复服务失败: {service_id}, 错误: {e}")
            return False
    
    def _perform_service_recovery(self, service_id: str) -> bool:
        """执行服务恢复操作"""
        try:
            # 根据服务类型执行不同的恢复策略
            if 'hai' in service_id.lower():
                # HAI实例恢复
                return self._recover_hai_instance(service_id)
            elif 'api' in service_id.lower():
                # API服务恢复
                return self._recover_api_service(service_id)
            else:
                # 通用服务恢复
                return self._recover_generic_service(service_id)
        except Exception as e:
            logger.error(f"执行服务恢复失败: {service_id}, 错误: {e}")
            return False
    
    def _recover_hai_instance(self, instance_id: str) -> bool:
        """恢复HAI实例"""
        try:
            # 尝试重启HAI实例
            from .tencent_hai_api import get_hai_client
            hai_client = get_hai_client()
            
            # 检查实例状态
            status = hai_client.get_instance_status(instance_id)
            if status == "STOPPED":
                # 启动实例
                return hai_client.start_instance(instance_id)
            elif status == "ERROR":
                # 重新创建实例
                return hai_client.recreate_instance(instance_id)
            else:
                logger.info(f"HAI实例状态正常: {instance_id}")
                return True
        except Exception as e:
            logger.error(f"恢复HAI实例失败: {instance_id}, 错误: {e}")
            return False
    
    def _recover_api_service(self, service_id: str) -> bool:
        """恢复API服务"""
        try:
            # 重启API服务
            import subprocess
            result = subprocess.run(['systemctl', 'restart', 'api-gateway'], 
                                  capture_output=True, text=True)
            return result.returncode == 0
        except Exception as e:
            logger.error(f"恢复API服务失败: {service_id}, 错误: {e}")
            return False
    
    def _recover_generic_service(self, service_id: str) -> bool:
        """恢复通用服务"""
        try:
            # 通用恢复策略：重启服务
            import subprocess
            result = subprocess.run(['systemctl', 'restart', service_id], 
                                  capture_output=True, text=True)
            return result.returncode == 0
        except Exception as e:
            logger.error(f"恢复通用服务失败: {service_id}, 错误: {e}")
            return False
    
    def get_fault_tolerance_status(self) -> Dict[str, Any]:
        """获取故障转移状态"""
        return {
            "auto_failover_enabled": self.auto_failover_enabled,
            "failed_services_count": len(self.failed_services),
            "failed_services": list(self.failed_services.keys()),
            "recovery_attempts": dict(self.recovery_attempts),
            "health_status": self.health_checker.get_health_status(),
            "recent_faults": self.health_checker.get_fault_events(5)
        }


# 全局实例
health_checker = None
fault_tolerance_manager = None


def initialize_fault_tolerance(structured_logger, load_balancer, hai_client):
    """初始化故障转移机制"""
    global health_checker, fault_tolerance_manager
    
    health_checker = HealthChecker(structured_logger)
    fault_tolerance_manager = FaultToleranceManager(health_checker, load_balancer, hai_client, structured_logger)
    
    return health_checker, fault_tolerance_manager


if __name__ == "__main__":
    # 测试代码
    logging.basicConfig(level=logging.INFO)
    
    # 创建模拟日志记录器
    class MockLogger:
        def log_alert(self, **kwargs):
            print(f"Alert: {kwargs}")
    
    # 测试健康检查
    checker = HealthChecker(MockLogger())
    
    # 注册测试服务
    def test_service_check():
        import random
        return random.choice([True, False])  # 随机返回健康状态
    
    checker.register_service("test_service", "api", test_service_check)
    checker.start()
    
    # 测试故障转移管理
    manager = FaultToleranceManager(checker, None, None, MockLogger())
    manager.start()
    
    # 运行一段时间
    time.sleep(10)
    
    # 获取状态
    health_status = checker.get_health_status()
    fault_status = manager.get_fault_tolerance_status()
    
    print(f"健康状态: {health_status}")
    print(f"故障转移状态: {fault_status}")
    
    # 停止
    checker.stop()
    manager.stop()
    print("故障转移测试完成")
